Isolated lunocapitate osteoarthritis-an alternative pattern of osteoarthritis

Scaphoid, lunate and capitate kinematics in the normal and ligament deficient wrist: A bi-plane X-ray fluoroscopy study

The ligamentous structures of the wrist stabilise and constrain the interactions of the carpal bones during active wrist motion; however, the three-dimensional translations and rotations of the scaphoid, lunate and capitate in the normal and ligament deficient wrist during planar and oblique wrist motions remain poorly understood. This study employed a computer-controlled simulator to replicate physiological wrist motion by dynamic muscle force application, while carpal kinematics were simultaneously measured using bi-plane x-ray fluoroscopy. The aim was to quantify carpal kinematics in the native wrist and after sequential sectioning of the scapholunate interosseous ligament (SLIL) and secondary scapholunate ligament structures. Seven fresh-frozen cadaveric wrist specimens were harvested, and cycles of flexion-extension, radial-ulnar deviation and dart-thrower's motion were simulated. The results showed significant rotational and translational changes to these carpal bones in all stages of disruptions to the supporting ligaments (p < 0.05). Specifically, following the disruption of the dorsal SLIL (Stage II), the scaphoid became significantly more flexed, ulnarly deviated, and pronated relative to the radius, whereas the lunate became more extended, supinated and volarly translated (p < 0.05). Sectioning of the dorsal intercarpal (DIC), dorsal radiocarpal (DRC), and scaphotrapeziotrapezoid (STT) ligaments (Stage IV) caused the scaphoid to collapse further into flexion, ulnar deviation, and pronation. These findings highlight the importance of all the ligamentous attachments that relate to the stability of the scapholunate joint, but more importantly, the dorsal SLIL in maintaining scapholunate stability, and the preservation of the attachments of the DIC and DRC ligaments during dorsal surgical approaches. The findings will be useful in diagnosing wrist pathology and in surgical planning.

Does Midcarpal Joint Structure Affect Development of Arthritis in the Wrist

Background  Degenerative wrist arthritis develops in specific patterns because of forces acting on existing structural configurations. The most common pattern of wrist osteoarthritis is scapholunate advanced collapse (SLAC). Other patterns include isolated scaphotrapezial trapezoid (STT) joint and isolated midcarpal or radiolunate joint arthritis. One predictor of degeneration pattern is the structure of the wrist. Questions/Purposes  Our purpose was to evaluate the relationship between midcarpal joint structure and the pattern of degenerative arthritis. We hypothesized that a wrist type 2 will preferentially develop SLAC degeneration. Patients and Methods  We retrospectively evaluated 195 degenerative wrist radiographs. Radiographs were reviewed for lunate/wrist type, degeneration pattern, ulnar variance, radial and volar tilt, inclination, carpal height, scapholunate angle, gap, and presence of thumb carpometacarpal (CMC) joint, STT joint, and midcarpal joint arthritis. Results  We had 158 radiographs with SLAC degeneration and 37 with atypical patterns, 154 type 2 and 41 type 1 wrists. There was a significant correlation between wrist type and the pattern of wrist degeneration ( p  = 0.02). SLAC degeneration developed in wrists with type 2 lunate while isolated midcarpal arthritis was associated with type 1 wrist. Isolated midcarpal joint arthritis was associated with STT arthritis, p  < 0.01. Radial height, inclination, volar tilt, and ulnar variance, and scapholunate gap and angle were not associated with wrist type. Ulnar variance was associated with thumb CMC and STT joint arthritis while radial height was associated with isolated midcarpal joint arthritis. Conclusion  This study found significant relationships between midcarpal joint structure and pattern of degeneration. This contributes to understanding the development of degeneration and can aid in future prevention of arthritis. Level of Evidence  This is a Level IV, diagnostic study.